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(No Model.) Z'Sheets-Sheet 1. F. H. MOLESWORTH.

PROCESS OF TREATING METALLIPEROUS ORES. No. 465,872. Patented 1390.29, 1891.

WITNESSES: /N VENTOH ATTORNEYS (No Model.) 2 sheets-sheet 2. F. H. MOLESWORTH.

PROCESS OF TREATING METALLIFEROUS 01153. No. 465,872. Patented Dec. 29, 1891.

WITNESSES: lNVE/YTOH mid, flaw; 915% 4 634? W BY I ATTORNEYS 1 0mm Perms co., vrmrmrma, WASNINGTGN o c rrrn STATES PAT NT rrice.

FRANCIS I-IYLTON lWIOLESlVORTH, OF ADELAIDE, SOUTH AUSTRALIA, ASSIGNOR TO GEORGE SPELLER IVRIGHT, CHARLES BALLARD, AND GEORGE MAR- SHALL, OF SAME PLACE.

PROCESS OF TREATlNG METALLIFEROUS ORES.

SPECIFICATION forming part of Letters Patent No. 465,872, dated December 29, 1891,

Application filed October 13, 1890. Serial No. 367,900. (No model.)

To ctZZ whom, it may concern." caused to enter at the outlet from which the Beit known that I, FRANCISIIYLTONMOLES- ore escapes at the conclusion of the operation. "WORTH, analytical chemist, a subject of the The gases formed in the calciner by the com- Queen ofGreat Britain, and residing at Adebustion of the oxidized sulphides are carried 5 1aide,in the Province of South Australia, have into a condensing-chamber. The nitro-sulinvented new and useful Improvements in pho-hydrochlorie acid therein obtained is used the Process of Treating Metalliferous Ores, of later as a solvent for the separation of the which the followingis a full, clear, and exact gold from the gangue and the peroxide given description. off in the operation utilized by being conro My invention relates to certain improve ducted to the calciner.

ments in the treatment of metalliferous ores, The term nitro-sulpho-hydrochloric acid and more particularly gold and silver bearis a name used by me to express the mea ing or other ores containing sulphides or archanieal mixtures of these acids. senides. In the following description the pro- For the purpose of carrying my invention [5 cess is, for convenience, described with referinto effect the calciner may either be rotary ence to gold-bearing ores, slight modifications or of the stationary bed type; but I prefer of detail being only necessary to render it apthe rotary form, and more particulary one to plicable to silver-bearing and other ores. which the heat is applied from the outside,

The special object of my invention is to proand the atmosphere by a forced draft caused 20 vide a means for the more expeditious reto enter at the escape-outlet of the ore. In

moval during the process of calcination of the this formof furnace the oxidizing properties sulphur, arsenic, or other substances which of the atmosphere are utilized to the fullest render difficult the extraction of the metals extent without being neutralized by the gases contained in the ores. arising from the combustion of the fuel. By

2 5 The special features of my invention conan arrangement of the apparatus I make use sist in the application of a peroxide to the also of the heat of the furnace in order to obores during their calcination, and in the tain the peroxide given off by the nitrate of utilization, for the purpose of extracting the soda or other chemical in the presence of the gold contained therein, of the resultant fluid sulphuric or other acid.

30 obtained by the condensation of the oxidized In order that my invention may be the betgases given off during the process. By the ter understood, I will 110W proceed to describe use of my invention more rapid decompose the same in conjunction'with an apparatus tion of the sulphides is effected during the for carrying it into effect, and by reference to calcination than by any method at present in the accompanying drawings, in which- 3 5 use. As a further advantage, the pyrites or Figure I is a sectional elevation of the furother ores can be roasted at a low temperanace and apparatus complete; Fig. II,a front ture, and by this means the formation of the elevation of the same. respective salts of the base metals prevented. Similar letters refer to similar parts in both \Vhile claiming as my invention the appli figures.

4o cation of all peroxides which will answer the A is a calciner of any description, but pref purpose, I prefer in use the nitrogen peroxide erably rotary, with internal ledges for the pur go resulting from the decomposition, of crude nipose of distributing the ore B, external hoptrate of soda by the application of sulphuric per into which the raw crushed ore is fed in or hydrochloric acid and heat. Either of the ordinary way; 0, feed-screw or other me- 4 5 these acids may be used, but, being cheaper, chanieal device for delivering the ore in regw sulphuric acid is preferred. The peroxide lar quantities from the hopper B into the en- 5 thus obtained is introduced into a ealciner trance of the calcinerA; D, furnace; D',furin which the pyrites or other ores are being nace chamber in which the oalciner A rel'oasted by external heat, and is preferably volves; D opening in the wall of the furnace chamber for the purpose hereinafter described; D furnace-flues; D, chimney or stack; E, discharging chute or hopper into which the oxidized ore from the calciner A is automatically'delivered F, exhaust-pipe leadingfrom the entrance of the calciner A; G, condensing-chamber connected with the exhaust-pipe F; H, rotary fan or other mechanical exhaust connected with the condensing-chamber G and having an outlet into the chimney or stack D I, retort, the base of which is placed over the opening D I, connecting-pipe leading from the retort I and having its outlet opposite to the outlet of the calciner A; and X is a valve for closing the flue D when desired.

The method of carrying my process into effect by means of the before-described mechanical apparatus is as follows: The ore to be treated, having been reduced to suitable fineness by any known means, is fed into the hopper B and introduced in regular quantities by means of the feed-screwO into the entrance of the calciner A. The furnace D being placed underneath the charging end of the calciner A, the ore receives its greatest heat immediately upon entrance. The sulphur and arsenic contained therein readily take fire and are converted into sulphur dioxide and arsenious trioxide, the vapors of which escape through the exhaust-pipe F into the condensing-chamber G, the draft being assisted by the rotary fan or other exhaust H. The flames from the furnace D, filling the chamber D and enveloping the calciner A, keep its contents at a dull-red heat, the smoke and other products of the combustion of the fuel escaping through the fiue D ,into the chimney or stack D. The retort I being placed over the opening D the heat of the furnace causes the nitrate of soda and sulphuric or other acid with which it is charged to give off nitrogen peroxide. This vapor, escaping from the conncting pipe I, placed preferably opposite the outlet of the calciner A, mixes with the atmospheric air, and being drawn therein speedily oxidizes any remaining traces of sulphur or arsenic contained in the ore under treatment. The speed at which the calciner is driven and the temperature of the charge as well as the quantity of peroxide supplied should be regulated according to the class of ore under treatment. The roasted pyrites when escaping into the discharge chute or hopper E will then be perfectly sweet and free from odor or fumes.

The nitrogen peroxide obtained from crude nitrate of soda containing a large percentage of chlorine forms, in combination with the sulphur dioxide in the condensing-chamber G, nitro-sulpho-hydrochloric acid. This liquid I propose to use as a solvent for the separation of the gold from the gangue obtained from the calciner by immersing the heated ore therein until the gold is dissolved.

I also wish it to be distinctly understood that I do not claim any portion of the withindescribed apparatus as part of my invention; but,

Having now particularly described and explained the nature of my said invention and in what manner the same is to be performed, I declare that what I claim is- The herein-described process, which consists in calcining ores of precious metals containing sulphides and arsenides, subjecting the roasting ore to the action of nitrogen peroxide, and subsequently passing the resultant gases through water, substantially as set forth.

In witness whereof I have hereunto set my hand in presence of two witnesses.

FRANCIS HYLTON lllOLESWOR'llI. IVitnesses:

E. B. CoLroN,

Solicitor, Adelaide, S. A. FRANCIS H. GROW,

Licensed Patent Agent, Adelaide. 

